Removing @author tags from reef-io
Merge pull request #952 from Microsoft-CISL/shravan_nggroup_del

Deprecating old group communication
Introducing ContextRepresenters

Closes #953

This PR introduces the new class `ContextRepresenters` which manages all the contexts on a single Evaluator. It is used by `EvaluatorManager` in lieu of the `List` and `Set` it used before. Furthermore, this adds `ContextFactory` which has the sole purpose of creating new `EvaluatorContext` instances for a given Evaluator.
Moved EvaluatorManager.State to be its own class EvaluatorState
Another fix for 763

This fix now keeps `EvaluatorManager` instances around and within them checks whether a received heartbeat shall be processed
Renamed the HelloREEF Job

this is part of #937, but not the full fix.
Results of code review with Shravan
Merge pull request #957 from Microsoft-CISL/weimer_937a

Renamed the HelloREEF Job
Merge pull request #954 from Microsoft-CISL/weimer_953

Introducing ContextRepresenters
Merge branch 'master' of https://github.com/Microsoft-CISL/REEF into weimer_763b
Code review with Shravan
Merge pull request #956 from Microsoft-CISL/weimer_763b

Another fix for 763
Made FailureREEF test use the TestEnvironment

This is a minor fix to make sure all tests in `reef-tests` use the test environment mechanism to setup the local or YARN runtime
Merge pull request #960 from Microsoft-CISL/weimer_unit_test_update

Made FailureREEF test use the TestEnvironment
Merge remote-tracking branch 'origin/master' into MLSS